How to split PDF by size using C#, VB.NET in WinForms?

The Syncfusion Essential® PDF is a .NET PDF library used to create, read, and edit PDF documents. With this library, you can split the PDF pages into multiple PDF documents based on the size using C# and VB.NET.

Steps to programmatically split the PDF pages into multiple PDF documents based on the size

1. Create a new C# Windows Forms application project.

2. Install the Syncfusion.Pdf.WinForms NuGet package as a reference to your .NET Framework application from NuGet.org.

3. Include the following namespaces in the Form.cs file.

   // [C# Code]
   using Syncfusion.Pdf.Parsing;
   using Syncfusion.Pdf;
   

' [VB Code]
Imports Syncfusion.Pdf.Parsing
Imports Syncfusion.Pdf

4. Use the following code sample to draw the table one after another in PDF.

   // [C# Code]
   //Document size 1MB.
   float sizeinKB = 1024;
    
   //Loads input PDF document.
   PdfLoadedDocument ldoc = new PdfLoadedDocument("../../data/pdf_document_reference.PDF");
    
   //Output document count.
   int documentCount = 1;
    
   int beginPageIndex = 0;
    
   //Initialize the PDF document.
   PdfDocument document = new PdfDocument();
    
   //Iterate the pages in the existing document.
   for (int i = 0; i < ldoc.Pages.Count; i++)
   {
   //Importing existing page to new document.
   document.ImportPage(ldoc, i);
    
   //Initialize memory stream.
   MemoryStream ms = new MemoryStream();
    
   //Save the document to stream.
   document.Save(ms);
    
   ms.Position = 0;
   if (sizeinKB * 1024 < ms.Length)
   {
   if (i == 0)
   {
   //Create a new file.
   FileStream fs = new FileStream(documentCount.ToString() + ".pdf", FileMode.Create);
   ms.CopyTo(fs);
   ms.Dispose();
   fs.Dispose();
   }
   else
   {
   //Initialize PDF document.
   document = new PdfDocument();
    
   //Import pages to the new document.
   document.ImportPageRange(ldoc, beginPageIndex, i - 1);
    
   //Save the document.
   document.Save(documentCount.ToString() + ".pdf");
    
   FileStream fileStream= File.OpenRead(documentCount.ToString() + ".pdf");
    
   //Close the document.
   document.Close(true);
   }
   documentCount++;
   beginPageIndex = i;
    
   //Initialize the document.
   document = new PdfDocument();
    
   if (i > 0)
   {
   //Import last page to new document.
   document.ImportPage(ldoc, i);
   }
   }
   else if (i == ldoc.Pages.Count - 1)
   {
   //Create a new file.
   FileStream fs = new FileStream(documentCount.ToString() + ".pdf", FileMode.Create);
   ms.CopyTo(fs);
   ms.Close();
   fs.Close();
   }
   }
   

'[VB Code]
'Document size 1MB.
Dim sizeinKB As Single = 1024
 
'Loads input PDF document.
Dim ldoc As New PdfLoadedDocument("../../data/pdf_document_reference.PDF")
 
'Output document count.
Dim documentCount As Integer = 1
 
Dim beginPageIndex As Integer = 0
 
'Initialize the PDF document.
Dim document As New PdfDocument()
 
'Iterate the pages in the existing document.
For i As Integer = 0 To ldoc.Pages.Count - 1
 
'Importing existing page to the new document.
document.ImportPage(ldoc, i)
 
'Initialize memory stream.
Dim ms As New MemoryStream()
 
'Save the document to stream.
document.Save(ms)
 
ms.Position = 0
If sizeinKB * 1024 < ms.Length Then
If i = 0 Then
 
'Create a new file.
Dim fs As New FileStream(documentCount.ToString() + ".pdf", FileMode.Create)
ms.CopyTo(fs)
ms.Dispose()
fs.Dispose()
Else
'Initialize PDF document.
document = New PdfDocument()
 
'Import pages to the new document.
document.ImportPageRange(ldoc, beginPageIndex, i - 1)
 
'Save the document.
document.Save(documentCount.ToString() + ".pdf")
 
Dim fileStream As FileStream = File.OpenRead(documentCount.ToString() + ".pdf")
 
'Close the document.
document.Close(True)
End If
documentCount += 1
beginPageIndex = i
 
'Initialize the document.
document = New PdfDocument()
 
If i > 0 Then
'Import last page to new document.
document.ImportPage(ldoc, i)
End If
ElseIf i = ldoc.Pages.Count - 1 Then
 
'Create a new file.
Dim fs As New FileStream(documentCount.ToString() + ".pdf", FileMode.Create)
ms.CopyTo(fs)
ms.Close()
fs.Close()
 
End If
Next

A complete working sample can be downloaded from SplitPDFC#-Sample.zip

By executing the program, the document has been spitted into multiple PDFs based on the given size. The console for output PDF size as follows,

Take a moment to peruse the documentation. You can find other options like insert, import, and splitting-a-pdf-file-to-individual-pages with Syncfusion® .NET PDF Library.

Refer here to explore a rich set of Syncfusion® .NET PDF features.

An online sample link explains how to split the PDF pages using C# and VB.NET into multiple PDF documents.